Method for producing multi-ply paper on a twin-wire machine

ABSTRACT

In apparatus for producing multi-ply paper by means of a pair of forming wires, the wires are arranged to travel horizontally toward each other and then to turn downwardly in converging relation. Multi-ply paper is produced by forming a separate sheet on each of the horizontally traveling reaches of wire and controlling the drainage of liquid through the wires to a low rate sufficient to maintain the consistency of the sheets at aproximately 5 to 12% so that they readily merge with each other as they travel into converging relation on the wires. A head box is provided above the converging portions of the wires for adding stock or other liquid to the converging sheets if desired.

Related US. Application Data Continuation of Ser. No. 252,573, May 12,1973, abandoned.

References Cited UNITED STATES PATENTS 1/1921 Monaghan 162/211 1/1936Reimer 162/348 X 11/1937 Sale 162/130 5/1971 Notbohm et al 162/203United States Patent 11 1 1111 3,915,791

Langdon [45] Oct. 28, 1975 METHOD FOR PRODUCING MULTI-PLY 3,867,2522/1975 Skrabak et al 162/203 PAPER ON A TWIN'WIRE MACHINE FOREIGNPATENTS OR APPLICATIONS 1751 Inventor: Eric Langdon, Haywards Heath1,904,962 8/1970 Germany 162/303 England [73] Assignee: The BlackClawson Company, P i y xamin s- L On BZ hOIe Fulton, N.Y. AssistantExaminerRichard V. Fisher [22] Filed: y 1974 Attorney, Agent, orFzrm-Brebel, French & Bugg In apparatus for producing multi-ply paper bymeans of a pair of forming wires, the wires are arranged to travelhorizontally toward each other and then to turn downwardly in convergingrelation Multi-ply paper is produced by forming a separate sheet on eachof the horizontally traveling reaches of wire and controlling thedrainage of liquid through the wires to a low rate sufficient tomaintain the consistency of the sheets at aproximately 5 to 12% so thatthey readily merge with each other as they travel into convergingrelation on the wires. A head box is provided above the convergingportions of the wires for adding stock or other liquid to the convergingsheets if desired.

3 Claims, 1 Drawing Figure US. Patent Oct. 28, 1975 Q7 x w METHOD FORPRODUCING MULTI-PLY PAPER ON A TWIN-WIRE MACHINE RELATED APPLICATIONThis application is a continuation of application Ser. No. 252,573 filedMay 12, 1973, now abandoned.

BACKGROUND OF THE INVENTION Multi-ply paper has been produced for manyyears by means of a plurality of cylinder type paper machines, with theplies which are separately formed on the several cylinder molds beingsuperposed on a common felt and transported thereby to presses and otherfinishing stations. Many variations of this arrangement have beenattempted, but in each case, the separate plies have been relativelywell formed before they were combined, and the bond between contiguousplies have been more the result of pressure then of intermingling of thefibers in the adjacent surface portions of the plies.

Another prior art approach, involving the use of basic Fourdrinier papermachine construction, has been to apply multiple layers of paper makingstock on the same forming wires through the use of successive headboxes.Due to the fact that the first ply drains freely through the formingwire so that the fibers therein felt out on the wire, drainage of eachsuccessive ply is appreciably retarded, and this necessitates the use ofa correspondingly long run of the wire. The same is true of multi-plymachines of the Fourdrinier type which use multiple wires, a typicalexample being shown in Thomas etal. U.S. Pat. No. 2,821,120.

More recently there has been increasing interest in the use of multiplewire paper machines in which the wires travel generally vertically, asfirst disclosed in Baxter U.S. Pat. No. Re. 24,333, and in theapplication of this general application to the production of multiplysheet. For example, Chupka U.S. Pat. No. 3,471,637 shows a multi-plypaper machine comprising a plurality of vertical forming zones, witheach successive ply being formed in one of these zones between a bareforming wire and the previously formed sheet carried by the other wire.Once again, this arrangement requires substantial wire length, as wellas substantial overall height for the machine.

SUMMARY OF THE INVENTION The present invention has as its primarypurpose the production of multi-ply paper wherein the adjacent plies areintimately bonded to each other by intermingling of the fibers composingthe surface portions of contiguous plies. The invention has theadditional objective of accomplishing this primary purpose by means of atwin wire paper machine which includes a vertical forming zone and whichdoes not differ substantially in overall dimensions from commercial twinwire single ply paper machines already in operation.

The invention accomplishes its purpose and objective by simultaneouslyforming a separate paper sheet on each of a pair of reaches of formingwire traveling linearly in opposite directions to a pair of turningrolls supported in closely spaced relation defining a gap therebetween.Drainage of liquid from the Sheets which form on these linearlytraveling reaches is retarded or otherwise controlled to a low rate suchthat the sheets are of relatively low consistency as they reach theirrespective turning rolls.

The two wires are caused to loop portions of the respective turningrolls and then to travel downwardly in closely spaced convergingrelation. In the resulting tapered merging zone, the sheets are forcedgently together so that the fibers in their opposed surface portionsintermingle as these surfaces are brought into contact and additionalliquid is extruded through the converging wires, so that major drainageof both plies takes place simultaneously while the plies are being urgedinto increasingly intimate contact. If desired, additional liquid, whichmay comprise paper making stock, may be delivered from above through thegap between the turning rolls to effect dilution of the opposed surfaceportions of the two plies and correspondingly increased intermingling ofthe fibers in those surface portions.

The primary objects of this invention are to provide a method andapparatus as outlined above for producing multi-ply paper sheet.Additional objects and advantages will in part be apparent and in partbe pointed out in the course of the following detailed description.

BRIEFDESCRIPTION OF THE DRAWINGS The single view is a side elevationillustrating diagrammatically a form of multi-ply paper making machineconstructed in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the twin-wire paper machineshown in the drawing, the lefthand forming wire 10 is looped around abreast roll 11, a turning roll 12, a suction couch roll 13, anadditional turning roll 14 and a guide roll 15, and it is also providedwith a tensioning roll 16. The righthand wire 20 is similarly loopedaround its breast roll 21, first turning roll 22, additional turningrolls 23-24 and guide roll 25, and it is provided with a tensioning roll26. The term wire is used herein as generically including a foraminousforming web of any material suitable for the purpose.

The two first turning rolls l2 and 22, which are in the positionscustomarily occupied by the breast rolls of a twin-wire single ply papermachine, are supported with their axes preferably in the same horizontalplane and with their closest surface areas controlably spaced to definea vertically extending narrow gap 30, for example a gap of the order ofl to 2 inches in horizontal width. The breast rolls 1 l and 21 aresupported in such relation with their associated first turning rolls sothat the reaches of wires 10 and 20 between rolls 11-12 and 21-22respectively travel towards each other along substantially linear paths.

The wires 10 and 20 are guided to wrap portions of their respectiveturning rolls and then to travel downwardly through the gap 30 intoclosely spaced relation along converging paths defining a merging zone33 of tapered section. This guiding action is supplied in part by thecouch roll 13 and turning roll 23, but primarily by the wire supportingdeflector blades 35, which may be of any suitable design satisfactoryfor use in a single ply twin wire paper machine. These deflector areshown as having adjustable mounting assemblies 36 of the type disclosedin McCarrick et al. U.S. Pat. No. 3,578,561 but they may be of otherforms, for example as shown in Baxter et al. U.S. Pat. No. 3,215,594. Inaddition to the deflectors 35, a suction box 37 is mounted within theloop of the wire above the couch roll 22.

A headbox 40 is supported to deliver paper making stock onto the wire 10on the off-running side of breast roll 11. The construction andarrangement of headbox 40 may be of any type conventionally used on aFourdrinier paper machine, and liquid from the stock delivered therebyonto the wire 10 will drain through the wire to form a paper sheet onthe reach of wire traveling to the turning roll 12. It is important tothe objectives of the invention, however, that the consistency of thisnewly formed paper sheet be controlled to a level low enough to providefor the subsequent bonding of additional plies when it travels aroundthe turning roll 12. This result is aided by the provision of arelatively short wire run between rolls 11 and 12, for example adistance of 10 feet or less. It can also be aided positively bysupporting the linear wire reach by means 42, such as forming boards orfoils, which tend to control drainage through the wires into thecollecting pan 43.

The wire is similarly provided with a headbox 44, drainage control means45 and collecting pan 46 for effecting formation of a relatively lowconsistency paper sheet on the linear reach between rolls 21 and 22.Preferably the consistency of each of these newly formed sheets shouldnot be significantly greater than is necessary to cause the sheets to beretained on the wires as they travel around the turning rolls 12 and 22,namely a consistency in the range of 5 to 12% depending in part on thespeed of the machine as well as on the character of the stock and thethickness of each ply.

It should be noted that the stock for each sheet need not be the same,and in a typical example, the stock from the headbox 40 may be designedto form top ply or liner, while the stock from headbox 44 is designed toform an under-ply or filler layer. In view of the extent of thesevariables, there may be conditions where it is necessary to control theconsistency of one or both of the plies by applying vacuum to the sheetduring its initial formation, and the drainage control means 42 and 45are to be correspondingly construed as including suction boxes suitablefor such purposes.

With the two newly formed sheets as described, their opposed surfaceportions readily intermingle as they are carried into contact with eachother in the merging zone. Further, with the wire runs which define themerging zone guided as described along closely spaced converging paths,the two paper sheets are forced gently together as the fibersintermingle and as addi tional water is extruded from the zone throughboth wires. It is especially desirable in this connection that thedeflectors 35 be arranged in vertically staggered relation such thateach deflector blade occupies a generally horizontal plane which isspaced vertically from the similar plane occupied by the nearestdeflectors on the opposite side of the forming zone, for example by adistance of the order of 6 inches in each direction. With thisarrangement, as one wire passes the edge of any of the deflectors, itwill be drawn tightly around the deflector, but the other wire will beconstrained only by its tension, and therefore can move as may berequired to maintain the proper spacing between the wires as well as theproper pressure to effect the desired merging of the contacting surfaceportions of the two sheets. The two wires reach their closest relativespacing as they pass the lowermost deflector within the loop of the wire20. As they pass the suction box 37 with the sheet Sandwiched betweenthem, its suction action holds the sheet on the wire 10 while the wire20 diverges toward the roll 23. The wire 10 with the sheet thereon thenwraps the rolls l3 and 14, and the sheet is transferred to the carryingfelt 50 wrapping the pickup roll 51 which engages the wire 10 betweenrolls 14 and 16.

The paper machine is also shown in the drawing as provided with aheadbox 55 positioned immediately above the gap 30 between the turningrolls l2 and 24. This headbox may be of any construction found suitablefor use for twin-wire single ply vertical paper machines, and itprovides the machine with substantial versatility. For example, themachine can be used to produce single ply paper, with stock beingsupplied only to the headbox 55 and not to either of the headboxes 40and 44. Additionally, there may be instances in which all threeheadboxes will be used, particularly if it is found desirable to deliveradditional liquid to the zone where the sheets on the two wires firstcome into contact. This additional liquid may be white water or papermaking stock, since the headbox 55 can be used to deliver stock forforming a center ply between the sheets already present on wires 10 and20.

While the methods and forms of apparatus herein described constitutepreferred embodiments of the invention, it is to be understood that theinvention is not limited to these precise methods and forms ofapparatus, and that changes may be made therein without departing fromthe scope of the invention.

What is claimed is:

l. The process of producing multi-ply paper which comprises the stepsof:

a. continuously advancing reaches of a pair of looped forming wirestoward each other along substantially linear paths,

b. turning said wires downwardly at the adjacent ends of said paths anddirecting said downwardly turned wires into closely spaced relationalong converging paths defining a merging zone,

c. depositing paper making stock on each of said linear wire reaches fordrainage of the liquid therethrough during travel thereof along saidpaths and formation of a paper sheet on each said wire reach,

d. controlling the drainage of liquid through said wire reaches to arate sufficient to maintain the consistency of said sheets in a lowrange of approximately 5 to 12% as said sheets are carried by said wiresinto said merging zone, and

e. alternately suppo rting each of said wires at spaced locations alongsaid merging zone while maintain ing both of said wires under tensionsuch that at each said location the unsupported said wire can move asrequired to maintain pressure on said low consistency sheets causing theadjacent surface portions of said low consistency sheets to merge witheach other while the liquid in said sheets is extruded through saidwires.

2. The process as defined in claim 1 wherein said drainage controllingstep is carried out by retarding the drainage of liquid through saidlinear wire reaches.

3. The process as defined in claim 1 wherein the consistency of saidsheets as they approach said merging zone is not substantially greaterthan is required to retain said sheets on said wires throughout saidturning step.

Patent No. 3,915,791 Dated October '28, 1975 Inventor(s) Eric C LangdonIt is certified that error appears in the above-identified patent andthat said Letters Patentare hereby corrected as shown below:

On the first page, in item [63] change "1973" CO --l972 Column 1, line 7change "1973" to Signed and Scaled this twenty-third Of March 1976[SEAL] Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer (ummisxiun erufPatenlsand Trademarks

1. THE PROCESS OF PRODUCING MULTI-PLY PAPER WHICH COMPRISES THE STEPSOF: A. CONTINUOUSLY ADVANCING REACHES OF A PAIR OF LOOPED FORMING WIRESTOWARD EACH OTHER ALONG SUBSTANTIALLY LINEAR PATHS, B. TURNING SAIDWIRES DOWNWARDLY AT THE ADJACENT ENDS OF SAID PATHS AND DIRECTING SAIDDOWNWARDLY TURNED WIRES INTO CLOSELY SPACED RELATION ALONG CONVERGINGPATHS DEFINING A MERGING ZONE, C. DEPOSITING PAPER MAKING STOCK ON EACHOF SAID LINEAR WIRE REACHES FOR DRAINIGE OF THE LIQUID THERETHROUGHDURING TRAVEL THEREOF ALONG SAID PATHS AND FORMATION OF A PAPER SHEET ONEACH SAID WIRE REACH, D. CONTROLLING THE DRAINAGE OF LIQUID THROUGH SAIDWIRE REACHES TO A RATE SUFFICIENT TO MAINTAIN THE CONSISTENCY OF SAIDSHEETS IN A LOW RANGE OF APPROXIMATELY 5 TO 12% AS SAID SHEETS ARECARRIED BY SAID WIRES INTO SAID MERGING ZONE, AND E. ALTERNATELYSUPPORTING EACH OF SAID WIRES AT SPACED LOCATIONS ALONG SAID MERGINGZONE WHILE MAINTANING BOTH OF SAID WIRES UNDER TENSION SUCH THAT AT EACHSAID LOCATION THE UNSUPPORTED SAID WIRE CAN MOVE AS REQUIRED TO MAINTAINPRESSURE ON SAID LOW CONSISTENCY SHEETS CAUSING THE ADJACENT SURFACEPORTIONS OF SAID LOW CONSISTENCY SHEETS TO MERGE WITH EACH OTHER WHILETHE LIQUID IN SAID SHEETS IS EXTRUDED THROUGH SAID WIRES.
 2. The processas defined in claim 1 wherein said drainage controlling step is carriedout by retarding the drainage of liquid through said linear wirereaches.
 3. The process as defined in claim 1 wherein the consistency ofsaid sheets as they approach said merging zone is not substantiallygreater than is required to retain said sheets on said wires throughoutsaid turning step.